CA2976131C - Catalyzed ceramic candle filter and method for cleaning of off- or exhaust gases - Google Patents

Catalyzed ceramic candle filter and method for cleaning of off- or exhaust gases Download PDF

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Publication number
CA2976131C
CA2976131C CA2976131A CA2976131A CA2976131C CA 2976131 C CA2976131 C CA 2976131C CA 2976131 A CA2976131 A CA 2976131A CA 2976131 A CA2976131 A CA 2976131A CA 2976131 C CA2976131 C CA 2976131C
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filter
gas
scr
exhaust gas
engine exhaust
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CA2976131A
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CA2976131A1 (en
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Francesco Castellino
Lars Storm PEDERSEN
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Topsoe AS
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Haldor Topsoe AS
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8643—Removing mixtures of carbon monoxide or hydrocarbons and nitrogen oxides
    • B01D53/8646—Simultaneous elimination of the components
    • B01D53/865—Simultaneous elimination of the components characterised by a specific catalyst
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8643—Removing mixtures of carbon monoxide or hydrocarbons and nitrogen oxides
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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    • B01D53/8656—Successive elimination of the components
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
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    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
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    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
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    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
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    • B01J23/648—Vanadium, niobium or tantalum or polonium
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    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
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    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/58—Fabrics or filaments
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Materials Engineering (AREA)
  • Analytical Chemistry (AREA)
  • Biomedical Technology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Toxicology (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Catalysts (AREA)
  • Dispersion Chemistry (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Filtering Materials (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)

Abstract

Ceramic candle filter and use of the filter in the removal of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and nitrogen oxides being present in process off-gas or engine exhaust gas, the filter comprises a combined SCR and oxidation catalyst arranged at least on the dispersion side and/or with in wall of the filter, the combined SCR and oxidation catalyst comprises palladium, a vanadium oxide and titania.

Description

Title: Catalyzed ceramic candle filter and method for cleaning of off- or exhaust gases The present invention relates to ceramic candle filters and a method for cleaning of off- or exhaust gases. More par-ticularly, the invention provides a catalyzed ceramic can-dle filter for the removal of dust and particulate matter in a process gas and harmful components contained in the process gas. The catalyzed ceramic candle filter is in par-ticular useful in the cleaning of process or raw gas from industrial processes involving combustion, like the produc-tion of minerals, glass, cement, waste incineration, or from coal fired boilers and engines.
Ceramic filters in form of filter candles are used in many industries for removal of particulate matter from process gases. They are one of the most efficient types of dust collectors available and can achieve collection efficien-cies of more than 99% for particulates. The filters can be made from various ceramic materials comprising ceramic fi-bres made of alkali and alkaline earth silicates, or alumi-no silicates.
The high particulate removal efficiency of ceramic candle filters is partly due to the dust cake formed on the sur-faces of the candle filter and partly due to the candle filter composition and porosity. In order to provide suffi-cient filtration activity and an acceptable low pressure drop over the filter conventional ceramic candle filters have a porosity of between 70 and 90%. The wall thickness of those filters should be in the range of 10-20 mm for sufficient stability and mechanical strength.
2 Particle-containing process off-gas and engine exhaust gas often contains a plurality of pollutants, e.g. NON, vola-tile organic compounds (VOC), SO2, CO, NH3, dioxins and fu-rans, in concentrations that have to be reduced depending on local legislation. For this purpose, several convention-al methods are available. The abatement of gaseous contami-nants like NON, VOC, dioxins and furans can be effectively carried out by contact with a catalyst. In particular, va-nadium oxide-based catalysts are commonly used catalysts for NOõ reduction by selective reduction of NO, with NH3 in stationary and automotive applications.
This catalyst is active both in the oxidative removal of hydrocarbons (VOC) and in the selective catalytic reduction (SCR) of NOx by reaction with NH3.
In comparison to the precious metal catalysts, like the Pd catalyst, the vanadium oxide catalyst is less selective in the formation of CO2 and some amounts of CO are produced during the oxidation reactions. CO cannot be oxidized to 002 at a feasible reaction rate by contact with the vanadi-um oxide catalyst.
We have found that when providing the candle filter with a catalyst comprising both vanadium oxide and palladium re-sults in an effective oxidation of hydrocarbons and soot together with ammonia-SCR of NOx and a lower slip of ammo-nia and carbon monoxide from the filter.
Pursuant to this finding, the present invention provides
3 a ceramic candle filter suitable for the removal of partic-ulate matter in form of soot, ash, metals and metal com-pounds, together with hydrocarbons and nitrogen oxides be-ing present in process off-gas or engine exhaust gas, the filter comprises a combined SCR and oxidation catalyst ar-ranged at least on the dispersion side and/or within wall of the filter, the combined SCR and oxidation catalyst com-prises palladium, a vanadium oxide and titania.
The terms "dispersion side" and "permeate side" as used herein refer to the flow side of the filter facing the un-filtered exhaust gas and to flow side facing the filtered off- or exhaust gas, respectively.
The invention provides additionally a method for the remov-al of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and nitrogen oxides being present in process off-gas or engine exhaust gas, comprising the steps of providing a process off-gas or engine exhaust gas contain-ing a nitrogenous reductant or adding the nitrogenous re-ductant to the off- or exhaust gas;
passing the off-gas or the exhaust through a ceramic candle filter and capturing the particulate matter; and reducing amounts of soot in the particulate matter captured on the at least one particulate filter and reducing amounts of nitrogen oxides and hydrocarbons in the off- or exhaust gas by oxidation of the hydrocarbons and by selective cata-lytic reduction (SCR) of the nitrogen oxides with the ni-trogenous reductant in contact with a combined SCR and oxi-dation catalyst being arranged on the dispersion side and/or within wall of the filter, wherein the combined SCR
4 and oxidation catalyst comprises palladium, a vanadium ox-ide and titania.
The term "a vanadium oxide" or "vanadium oxide" refers to:
Vanadium(II)oxide (vanadium monoxide), VO; or vanadium(III)oxide (vanadium sesquioxide or trioxide), V203; or vanadium(IV)oxide (vanadium dioxide), V02; or vanadium(V)oxide (vanadium pentoxide), V205.
Preferably, vanadium oxide for use in the invention com-prises or consists of vanadium(V)oxide (vanadium pentox-ide), V205.
The term "titania" refers to titanium dioxide (Ti02).
The catalytically active form of palladium is palladium in the metallic and/or oxidic form.
The shortage Pd/V/Ti shall mean a catalyst consisting of palladium, a vanadium oxide and titania.
The Pd/V/Ti catalyst has i) dual functionality (removal of NOx and removal of VOC, volatile organic compounds); ii) a S-tolerance; and iii) a lower SO2 oxidation activity com-pared to other catalyst compositions, e.g. Pt-based cata-lysts.
When employing a Pd/V/Ti catalyst the catalyzed filter can-dles are sulfur resistant, i.e. not subjected to sulfur de-activation. The Pd/V/Ti catalyst additionally reduces the amount of SO3 formed by oxidation of SO2. If H2S is also
5 present in the process gas entering the filter, it will also be oxidized to SO2 on the Pd/V/Ti catalyst.
The catalytically active material may be applied on the ceramic filter by impregnation with a slurry containing the catalytically active material in form of titania micro-particles and the precursors of the active materials, i.e. salts of vanadium and palladium. Once impregnated, the filter is subsequently dried and heated up to the required temperature for the decomposition of all precursors and activation of the catalyst.
Compared to monolithic formed filters or wall flow filters, the effective gas contact between the palladium metal particles and reactants in gas is much higher, which results in a much reduced amount of palladium necessary to obtain a reasonable oxidation activity.
Typically, the catalyst employed in the invention the catalyst contains palladium in an amount of between 20 and 1000 ppm/weight of the filter, preferably less than 200 ppm/weight.
In the case of high temperature ceramic filters several types of fibers may be used for their production. These can be constituted e.g. by silica-aluminate, calcium-magnesium-silicates, calcium-silicates fibers, or a mixture thereof.
Other preferred ceramic fibres comprise bio-soluble fibres selected from the group of calcium-magnesium-silicates.
Date recue/Date Received 2020-09-23

Claims (6)

CLAIMS:
1. A ceramic candle filter suitable for the removal of particulate matter in the form of soot, ash, metals, and metal compounds, together with hydrocarbons and nitrogen oxides from process off-gas or engine exhaust gas, the filter comprising a combined selective catalytic reduction (SCR) and oxidation catalyst arranged at least on the dispersion side of the filter facing unfiltered gas and/or within a wall of the filter, the combined SCR and oxidation catalyst comprising palladium, a vanadium oxide and titania, wherein the ceramic material of the filter is produced from fibers selected from the group consisting of silica-aluminate fibers, calcium-magnesium-silicate fibers, calcium-silicate fibers, and mixtures thereof.
2. The ceramic candle filter of claim 1, wherein the catalyst contains palladium in an amount of between 20 and 1000 ppm/weight of the filter.
3. The ceramic candle filter according to claim 1 or 2, wherein the ceramic material of the filter consists of calcium-magnesium-silicate fibres that are bio-soluble.
4. A method for the removal of particulate matter in the form of soot, ash, metals, and metal compounds, together with hydrocarbons and nitrogen oxides from process off-gas or engine exhaust gas, comprising the steps of:
providing a process off-gas or engine exhaust gas containing a nitrogenous reductant or adding the nitrogenous reductant to the off-gas or the engine exhaust gas;
Date Recue/Date Received 2021-02-12 passing the off-gas or the engine exhaust gas through a ceramic candle filter and capturing the particulate matter;
and reducing amounts of soot in the particulate matter captured on the at least one particulate filter and reducing amounts of nitrogen oxides and hydrocarbons in the off-gas or engine exhaust gas by oxidation of the hydrocarbons and by selective catalytic reduction (SCR) of the nitrogen oxides with the nitrogenous reductant in contact with a combined SCR
and oxidation catalyst being arranged on the dispersion side of the filter facing unfiltered gas and/or within a wall of the filter, wherein the combined SCR and oxidation catalyst comprises palladium, a vanadium oxide and titania;
wherein the ceramic material of the filter is produced from fibers selected from the group consistin.g of silica-aluminate fibers, calcium-magnesium-silicate fibers, calcium-silicate fibers, and mixtures thereof.
5. The method according to claim 4, wherein the combined oxidation and SCR catalyst contains palladium in an amount of between 20 and 1000 ppm/weight of the filter.
6. The method according to claim 4 or 5, wherein the ceramic material of the filter comprises calcium-maghesium-silicate fibres that are bio-soluble.
Date Recue/Date Received 2021-02-12
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JP2018514367A (en) 2018-06-07
CN107427771A (en) 2017-12-01
CN107427771B (en) 2021-07-02
CA2976131A1 (en) 2016-09-29
US20180008964A1 (en) 2018-01-11
KR102424112B1 (en) 2022-07-25
KR20170128220A (en) 2017-11-22
WO2016150465A1 (en) 2016-09-29

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